Can someone advise why is there a long delay.
Please, re-visit this statement…
The availability of the firmware update depends on your firmware variant. The firmware variant is identified through your Product Code. With a Lumia 950 series phone, the Product Code is written underneath the battery cover (Code 59…). Microsoft Mobile wants you to wait until your phone notifies you about an update. This happens automatically. If you post your Product Code, the community is able to double-check your situation.